How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Doug Your Own Question
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8609
Experience:  Mitsubishi employed and Factory trained ASE certified technician
Type Your Mitsubishi Question Here...
Doug is online now
A new question is answered every 9 seconds

Mitsubishi Galant my girlfriend has a 2001 mitsubishi galant.

Customer Question

my girlfriend has a 2001 mitsubishi galant. one day we were driving and her upper radiator hose cracked. so i replaced the hose and refilled the coolant that leaked out. test drove it and it still started to overheat. Next i replaced the thermostat thinking that it might have burned out or became stuck, but it still started to overheat after that. from this point i am baffled, some people have told me she might have a blown head gasket. is that the only logical problem or could it be something else
Submitted: 6 years ago.
Category: Mitsubishi
Expert:  Doug replied 6 years ago.

There are two probable scenarios here.
1) Large air pocket in system
2) Blown headgasket

Obviously we want to start assuming to problem is just an air pocket as the head gasket is an expensive repair and not the "first thing" you want to go to.

That being said, when the radiator hoses fail completely (crack, burst, etc) it is normally due to a pre-existing over heat condition.

Before doing anything, check the oil in the vehicle to make sure there is no coolant contamination, indicating a head gasket failure. The oil should be clear/yellow, clear/brown or dark black depending on the condition/last oil change. If the oil is light brown/milky, looking like creamed coffee or a chocolate milkshake, this is indicating coolant contamination and the headgasket has failed.

Once that is checked and verified a non-issue, we can go to eliminating air pockets.
This is kind of a pain on this vehicle, but can be done with some patience and making a bit of a mess. If possible, I recommend using coolant fill funnels like this to aid in the process. They can be bought at most auto parts stores. Using this funnel, it seals to the top of the radiator, and effectively raises the "high point" of the cooling system as you can fill the bucket up with coolant. Raising the high point makes it easier for air pockets to work their way out.
It is not necessary however, it is just a bit messier without it.

Take a jack or ramps and elevate the front of the vehicle.
Remove the radiator cap (attach funnel if available)
Fill the radiator to the top if it isn't already
Start the vehicle and turn the heater to full hot
Standing over the engine, rev the engine to ~2500 rpm for 2-3 seconds then release.
Repeat this revving, each time you release air pockets will move around, hopefully finding their way to the radiator neck. If you have the coolant funnel on there, you will easily be able to watch the air pockets come out.
Continue this process, filling the radiator as necessary (some fluid will be pulled into the system as air is displaced, as well as some will be spilled while revving if you do not have the funnel attached).
Once you think you have it all out (this can take up to 20 minutes of bleeding air sometimes), squeeze the radiator hoses to push out in last air bubbles caught in the hoses, then reinstall the radiator cap.

Allow the system to cool down considerably, the restart the engine, watching the temperature gauge.
If the temperature stays normal, or is "better" you are fixed or nearly there.
If the temperature gauge immediately spikes upward, check the radiator hoses temperature. If the upper hose is cool/warm and the gauge is indicating an overheat, you still have significant air pockets.
If both hoses are very hot, you have flow and most likely will have a failed head gasket.

At that point you will want to have a shop verify this 100% prior to moving forward with a head gasket replacement (just in case you still didn't get all t he air out).
At a shop they will be able to do two CO tests on the coolant to verify a failure. One is a chemical additive poured into the radiator (some auto parts stores will sell this, not many though), and when it comes in contact with CO gases from a failed headgasket, it changes the color of the coolant. Second is a electronic CO detector which "sniffs" the coolant for evidence of CO from a failed head gasket. A condemnation from either of these tests would indicate time for a headgasket replacement and have the cylinder head checked at a machine shop for damage from overheating (warping, cracks).

For what it is worth, these are relatively tough head gaskets and can handle a lot of stress before failing. As long as the vehicle was not overheating prior to the hose failing... causing the hose failure... you are probably going to be OK with just having air pockets in there. If the hose ruptured -because- the vehicle was overheating first, then the likelihood of head gasket failure is much higher.